The water cycle, also known as the hydrologic cycle, is a continuous process by which water circulates through the Earth's atmosphere, oceans, and land. This cycle is essential for supporting all forms of life and maintaining the Earth's climate. Water undergoes various changes in state—evaporating from the surface, condensing in the atmosphere, and precipitating back to the surface. At its start, the sun heats up water in rivers, lakes, and oceans, causing it to evaporate and rise into the atmosphere as vapor. Once in the atmosphere, this vapor cools and condenses into clouds. Over time, these clouds get heavy and release precipitation in the form of rain, snow, or sleet, which falls back to the Earth's surface. Some of this precipitation collects in bodies of water, while some seeps into the soil, replenishing groundwater supplies. Additionally, some water returns to the atmosphere through transpiration, a process where water is released from plants. The cycle is critical not only for water distribution but also for transporting nutrients and purifying water naturally through filtration as it flows through different layers of the Earth's surface.